The idea is to add capabilities that are not currently built into handsets themselves.

But Sony's latest flagship phone also has new photography tricks of its own.

"It seems that people are holding on to their phones for longer, and, so, vendors are hoping to sell them extra things to add on," said Carolina Milanesi, a consumer tech analyst at Creative Strategies.

All three handsets offer several key improvements over the Z3 and Z4 series, and their arrival is easy the biggest news of IFA 2015. However, what you might not know is that Sony actually has a fourth Xperia Z5 family member on the way, at least according to the China-based tech site CnBeta.com.